1. Field of the Invention
The present invention relates to photoresist monomers, polymers derived therefrom and photoresist compositions containing such polymers. In particular, the present invention is directed to photoresist polymers and photoresist compositions containing such polymers which are not sensitive to the presence of environmental amine contaminants in a lithography process (e.g., using an ultraviolet light source) when fabricating a minute circuit for high integration semiconductor devices, and processes for preparing such photoresist polymers and photoresist compositions.
2. Description of the Background Art
Use of chemical amplification-type photoresists (i.e., photoresist compositions) is currently being investigated in photolithography processes to achieve a high sensitivity in minute image-formation on semiconductor devices. Such photoresists are generally prepared by blending a photoacid generator with a matrix resin polymer (i.e., photoresist polymer) having an acid labile group.
In a photolithography process for producing semiconductor devices, the resolution of an image depends on the wavelength of the light used. Thus, the shorter the wavelength, higher the resolution, i.e., shorter wavelengths allow smaller pattern formation.
In order to be useful in a photolithography process, a photoresist (PR) must have an excellent etching and heat resistance, and adhesiveness. Moreover, to reduce the cost of manufacturing semiconductor devices, a PR should be capable of being developed in a common developing solution, such as a 2.38 wt % aqueous tetramethylammonium hydroxide (TMAH) solution. These qualities are particularly important in photolithography processes utilizing a short wavelength light source including KrF (248 nm), ArF (193 nm), VUV (157 nm) and EUV (13 nm).
While it is difficult to synthesize a photoresist polymer that satisfies all of these requirements, a variety of photoresist polymers with improved etching resistance, adhesiveness and resolution have been developed. Unfortunately, however, most chemically-amplified photoresists currently available have a relatively short post exposure delay (PED) stability. In general, when there is delay between exposure of the photoresist to light and development of the exposed photoresist, acids that are generated on the exposed area are neutralized by amine compounds which may be present in the production atmosphere. Since the pattern formation depends on acids that are generated by the exposure, neutralization of acids by atmospheric amine compounds reduce, prevent or alter a pattern formation, e.g., a T-topping phenomenon may occur where the top portion of the pattern forms a T-shape.
It is therefore an object of the present invention to provide a photoresist monomers having an enhanced PED stability.
Another object of the present invention is to provide PR polymers using the PR monomers described above and a process for preparing the same.
Another object of the present invention is to provide photoresist compositions using the PR polymers described above, and a process for preparing the same.
Still another object of the present invention is to provide a semiconductor device produced by using the above described PR composition.